Indian Space Program: News & Discussion
Re: Indian Space Program: News & Discussion
@mods, can you please enforce the rule w.r.t. posting YT videos without description of the content
Re: Indian Space Program: News & Discussion
Why don't you put up your description, instead of complaining about me?
Are you paying for my time, for me to do this extra work for you?
Last edited by Suraj on 17 Oct 2024 22:41, edited 1 time in total.
Reason: Poster banned for one week for continuous disruptive behavior. Next infacrtion will result in a permanent ban.
Reason: Poster banned for one week for continuous disruptive behavior. Next infacrtion will result in a permanent ban.
Re: Indian Space Program: News & Discussion
Pogo Oscillations in Human Spaceflight
In this short note I want to broach the subject of pogo oscillations. Why they arise and how they plagued early human spaceflight almost preventing the US mission to the Moon. They again appeared in some Shuttle Missions and can appear again when countries like India take their first steps towards manned missions. It will become clearer which missions may be affected by pogo oscillations. I shall not invoke anything from Aeroelasticity or Aircraft structures all of which I know cold. But shall try to explain in a rudimentary manner. First the pogo stick is a well known toy used by both children and adults. Here is a video, it is important to note that the oscillations are occuring logitudinally along the pogo stick and not transverse.
https://www.youtube.com/watch?v=UWzjea68dAI
Why do Pogo Oscillations occur in Spacecraft
The commonest cause of pogo oscillations is due to non uniform combustion in cryogenic engines or even hypergolic engines where two corrosive fluids combine to ignite and provide propulsion like the Titan rockets that powered the Gemini 2 man missions. Typically they can occur when there is positive feedback, a small change in the rate of fuel supplied to the combustion chamber leads the spacecraft to accelarate, that put pressure on the fuel tanks and pumps that pump in more fuel and the spacecraft accelarates even more, at some point the cycle cannot sustain itself and there is a decelaration and then again the cycle repeats. So we have oscillatory motion. All this happens extremely quickly as will be discussed in the next section. A toy model for this phenomenon is given by the ordinary differential equation,
y"(t)+y(t)= 2a cos t
Yes indeed, this is the model for Resonance. So even though a is a tiny number which means the force on the mass-spring system is periodic with a small amplitude, because the frequency of the applied force matches the natural frequency of the mass spring system, using any favorite way to solve the equation either undetermined coefficients or variation of parameters, leads to the solution
y(t)= a t sin t. And so you see the solution has an amplitude that is a t that is increasing massively in time. As you can see this has a disastrous consequence which means the accelaration will increase though in an oscillatory way due to the sin t term in the solution. The g forces on the astronauts will mount leading to incapacitation and eventually death of the astronauts. At the very least the structural integrity of the spacecraft may be destroyed due to the mounting g forces. All this is NOT science fiction and has happened in NASA spaceshots that we discuss below. This is a brief outline of how pogo oscillations arise.
Pogo Oscillations in Human Spaceflight.
Let us now focus on some missions where pogo oscillations were intense leading to a period of flight where there was extreme concern that the mission was lost.
In early tests with the Titan engine conducted by USAF one found:
The USAF began test flights with the Titan II ballistic missile on March 16, 1962. Ninety seconds into the
first-stage flight the missile began a longitudinal vibration going from 10-13 Hertz for roughly 30 seconds(pogo oscillations begin at 90 seconds) reaching a maximum amplitude of +/- 2.5 g’s at about 11 Hertz.2,3,4 Even for a military payload this design
environment was excessive (the USAF considered 1.0 g as a tolerable design load for the structure of the Titan
II and it’s payload). 2,4 But for a spacecraft’s crew, vibration at 11 Hertz and +/- 2.5 g’s could be painful and
would greatly impair their ability to perform any piloting functions or respond to an emergency. NASA
required that the vibrations be kept below +/- 0.25 g’
The frequency of oscillation is quite severe and for human spaceflight NASA deemed that pogo oscillations be kept at 0.25g or less.
The Martin company prime contractors for the engine thought they had a solution but in fact the solution now worsened the problem and the oscillations went up to 5g
The longitudinal oscillations were soon given the nickname “pogo”, because of the analogy to the ride on the
children’s pogo stick jumping toy. Pogo was a regular discussion item in Houston at the NASA Manned
Spacecraft Center (MSC) and the USAF formed a special Committee for Investigation of Missile Oscillations.
The fourth Titan II test flight in July 1962 provided engineers with a clue to the problem as the
implementation of a higher operating pressure in the first-stage fuel tank seemed to have cut the pogo
amplitude in half, to 1.25 g’s.1
The Titan II contractor, The Martin Company, suggested that pogo might be caused by oscillating pressures in
the propellant feedlines. Using what was thought to be an accurate mathematical model, Martin proposed to
install a vertical surge-suppression standpipe charged with gaseous nitrogen in each of the oxidizer lines on a
NASA Experience with Pogo in Human Spaceflight Vehicles
5 - 4 RTO-MP-AVT-152
later Titan II test flight. NASA endorsed the plan, and the USAF agreed, launching the eighth Titan II
development flight (N-11) on December 6, 1962 with the standpipes installed.1,2,3
But instead of damping the pogo effect, the vibrations at the payload actually increased to +/-5 g’s, forcing an
early first stage engine shut down and mission loss. The NASA MSC Director remarked to his Manned Space
Flight Management Council that he saw one hope: "the fact that the addition of the surge chamber affected the
oscillation problem may indicate that the work is being done in the right place."
Some sort of solution was implemented, did it cure the problem. NO
It started with Gemini V with Pete Conrad and Virgil Grissom with 126 seconds of intense pogo oscillations and remarkably the booster phase engineers saw nothing on telemetry. Both astronauts suffered speech and vision problems during the time they were buffeted by pogo. Post flight it was discovered that the oscillations stemmed from the oxidizer side and not fuel side. Recall what I said, that the Titan was using hypergolic fuels not cryogenic.
The postflight reports for Gemini X and XII noted
intermittent suppressed longitudinal oscillation at T+123 seconds, at 10.9 Hz and +/-0.10 g; and at T+126.1
seconds at 11.2 Hz and +/-0.14 g, respectively. So you see that pogo oscillations were never completely eliminated on Project Gemini.
Project Apollo and the Saturn Engine
This was von Braun's baby and was supposed to fly humans to the Moon. The engine was cryogenic. But now the problem was vacuum bubbles in fuel lines that started off pogo oscillations. The Saturn engines were detuned as a design step. That is no two engines had the same frequency so as to create a resonance situation like in the toy model ordinary differential equation I wrote down earlier. But nevertheless pogo appeared on the unmanned Apollo 6.
Apollo 6, launched on April 4, 1968, but
unexpectedly experienced pogo at 5 Hz between 105-140 seconds during first stage (S-IC) boost with 0.60 g
maximum acceleration at the command module and 0.33 g at the aft of the vehicle.3 The second and third
stages of flight also experienced problems with failures of the J-2 engines unrelated to the first stage pogo.
At this point it was suggested to inject Helium into the vacuum bubbles in the fuel lines. von Braun went so far as to state that the Moon mission was doomed.
It was known that the Saturn first stage F-1 engines exhibited combustion chamber vibration at about 5-1/2
Hz. As vehicle mass reduced during flight the frequency of structural vibrations coincided with the engine
frequency, causing closed-loop coupling of the oxidizer feed system and the vehicle first longitudinal mode,
resulting in pogo.
So there you see as the mass decreased due to burning off of fuel, resonance as described by my differential equation set in. Helium injection was tried. Note it is always the oxidizer side of the fuel system that created the problem. Usually a standpipe in the oxidizer side.
These problems and ingenious solution which I will not go into further, was implemented into Apollo 8 which was the first mission to the Moon which was a flyby with human beings. It worked well though the second stage experienced pogo at 12Hz and the first stage underperformed and so the burn was longer.
In part NASA had created a special pogo task force constituting members from industry and academia for an intensive investigation. At one time during the pogo studies, the Saturn V manager is reported to have said that 1,000 engineers from government and industry were working on the problem.
Was the problem solved for all time? No. Pogo came back on Apollo 13 and future shuttle missions.
Hope ISRO has also licked the problem or at least contained it so that it is not a hazard to the astronauts and the space vehicle.
Regarding Gemini 7, at T+ 110 seconds Frank Borman commander experienced pogo but gentler, though his co-pilot Jim Lovell did not notice any. Both with team with Bill Anders n Apollo 8 to fly to the Moon in the first human flyby of the Moon.
In this short note I want to broach the subject of pogo oscillations. Why they arise and how they plagued early human spaceflight almost preventing the US mission to the Moon. They again appeared in some Shuttle Missions and can appear again when countries like India take their first steps towards manned missions. It will become clearer which missions may be affected by pogo oscillations. I shall not invoke anything from Aeroelasticity or Aircraft structures all of which I know cold. But shall try to explain in a rudimentary manner. First the pogo stick is a well known toy used by both children and adults. Here is a video, it is important to note that the oscillations are occuring logitudinally along the pogo stick and not transverse.
https://www.youtube.com/watch?v=UWzjea68dAI
Why do Pogo Oscillations occur in Spacecraft
The commonest cause of pogo oscillations is due to non uniform combustion in cryogenic engines or even hypergolic engines where two corrosive fluids combine to ignite and provide propulsion like the Titan rockets that powered the Gemini 2 man missions. Typically they can occur when there is positive feedback, a small change in the rate of fuel supplied to the combustion chamber leads the spacecraft to accelarate, that put pressure on the fuel tanks and pumps that pump in more fuel and the spacecraft accelarates even more, at some point the cycle cannot sustain itself and there is a decelaration and then again the cycle repeats. So we have oscillatory motion. All this happens extremely quickly as will be discussed in the next section. A toy model for this phenomenon is given by the ordinary differential equation,
y"(t)+y(t)= 2a cos t
Yes indeed, this is the model for Resonance. So even though a is a tiny number which means the force on the mass-spring system is periodic with a small amplitude, because the frequency of the applied force matches the natural frequency of the mass spring system, using any favorite way to solve the equation either undetermined coefficients or variation of parameters, leads to the solution
y(t)= a t sin t. And so you see the solution has an amplitude that is a t that is increasing massively in time. As you can see this has a disastrous consequence which means the accelaration will increase though in an oscillatory way due to the sin t term in the solution. The g forces on the astronauts will mount leading to incapacitation and eventually death of the astronauts. At the very least the structural integrity of the spacecraft may be destroyed due to the mounting g forces. All this is NOT science fiction and has happened in NASA spaceshots that we discuss below. This is a brief outline of how pogo oscillations arise.
Pogo Oscillations in Human Spaceflight.
Let us now focus on some missions where pogo oscillations were intense leading to a period of flight where there was extreme concern that the mission was lost.
In early tests with the Titan engine conducted by USAF one found:
The USAF began test flights with the Titan II ballistic missile on March 16, 1962. Ninety seconds into the
first-stage flight the missile began a longitudinal vibration going from 10-13 Hertz for roughly 30 seconds(pogo oscillations begin at 90 seconds) reaching a maximum amplitude of +/- 2.5 g’s at about 11 Hertz.2,3,4 Even for a military payload this design
environment was excessive (the USAF considered 1.0 g as a tolerable design load for the structure of the Titan
II and it’s payload). 2,4 But for a spacecraft’s crew, vibration at 11 Hertz and +/- 2.5 g’s could be painful and
would greatly impair their ability to perform any piloting functions or respond to an emergency. NASA
required that the vibrations be kept below +/- 0.25 g’
The frequency of oscillation is quite severe and for human spaceflight NASA deemed that pogo oscillations be kept at 0.25g or less.
The Martin company prime contractors for the engine thought they had a solution but in fact the solution now worsened the problem and the oscillations went up to 5g
The longitudinal oscillations were soon given the nickname “pogo”, because of the analogy to the ride on the
children’s pogo stick jumping toy. Pogo was a regular discussion item in Houston at the NASA Manned
Spacecraft Center (MSC) and the USAF formed a special Committee for Investigation of Missile Oscillations.
The fourth Titan II test flight in July 1962 provided engineers with a clue to the problem as the
implementation of a higher operating pressure in the first-stage fuel tank seemed to have cut the pogo
amplitude in half, to 1.25 g’s.1
The Titan II contractor, The Martin Company, suggested that pogo might be caused by oscillating pressures in
the propellant feedlines. Using what was thought to be an accurate mathematical model, Martin proposed to
install a vertical surge-suppression standpipe charged with gaseous nitrogen in each of the oxidizer lines on a
NASA Experience with Pogo in Human Spaceflight Vehicles
5 - 4 RTO-MP-AVT-152
later Titan II test flight. NASA endorsed the plan, and the USAF agreed, launching the eighth Titan II
development flight (N-11) on December 6, 1962 with the standpipes installed.1,2,3
But instead of damping the pogo effect, the vibrations at the payload actually increased to +/-5 g’s, forcing an
early first stage engine shut down and mission loss. The NASA MSC Director remarked to his Manned Space
Flight Management Council that he saw one hope: "the fact that the addition of the surge chamber affected the
oscillation problem may indicate that the work is being done in the right place."
Some sort of solution was implemented, did it cure the problem. NO
It started with Gemini V with Pete Conrad and Virgil Grissom with 126 seconds of intense pogo oscillations and remarkably the booster phase engineers saw nothing on telemetry. Both astronauts suffered speech and vision problems during the time they were buffeted by pogo. Post flight it was discovered that the oscillations stemmed from the oxidizer side and not fuel side. Recall what I said, that the Titan was using hypergolic fuels not cryogenic.
The postflight reports for Gemini X and XII noted
intermittent suppressed longitudinal oscillation at T+123 seconds, at 10.9 Hz and +/-0.10 g; and at T+126.1
seconds at 11.2 Hz and +/-0.14 g, respectively. So you see that pogo oscillations were never completely eliminated on Project Gemini.
Project Apollo and the Saturn Engine
This was von Braun's baby and was supposed to fly humans to the Moon. The engine was cryogenic. But now the problem was vacuum bubbles in fuel lines that started off pogo oscillations. The Saturn engines were detuned as a design step. That is no two engines had the same frequency so as to create a resonance situation like in the toy model ordinary differential equation I wrote down earlier. But nevertheless pogo appeared on the unmanned Apollo 6.
Apollo 6, launched on April 4, 1968, but
unexpectedly experienced pogo at 5 Hz between 105-140 seconds during first stage (S-IC) boost with 0.60 g
maximum acceleration at the command module and 0.33 g at the aft of the vehicle.3 The second and third
stages of flight also experienced problems with failures of the J-2 engines unrelated to the first stage pogo.
At this point it was suggested to inject Helium into the vacuum bubbles in the fuel lines. von Braun went so far as to state that the Moon mission was doomed.
It was known that the Saturn first stage F-1 engines exhibited combustion chamber vibration at about 5-1/2
Hz. As vehicle mass reduced during flight the frequency of structural vibrations coincided with the engine
frequency, causing closed-loop coupling of the oxidizer feed system and the vehicle first longitudinal mode,
resulting in pogo.
So there you see as the mass decreased due to burning off of fuel, resonance as described by my differential equation set in. Helium injection was tried. Note it is always the oxidizer side of the fuel system that created the problem. Usually a standpipe in the oxidizer side.
These problems and ingenious solution which I will not go into further, was implemented into Apollo 8 which was the first mission to the Moon which was a flyby with human beings. It worked well though the second stage experienced pogo at 12Hz and the first stage underperformed and so the burn was longer.
In part NASA had created a special pogo task force constituting members from industry and academia for an intensive investigation. At one time during the pogo studies, the Saturn V manager is reported to have said that 1,000 engineers from government and industry were working on the problem.
Was the problem solved for all time? No. Pogo came back on Apollo 13 and future shuttle missions.
Hope ISRO has also licked the problem or at least contained it so that it is not a hazard to the astronauts and the space vehicle.
Regarding Gemini 7, at T+ 110 seconds Frank Borman commander experienced pogo but gentler, though his co-pilot Jim Lovell did not notice any. Both with team with Bill Anders n Apollo 8 to fly to the Moon in the first human flyby of the Moon.
Re: Indian Space Program: News & Discussion
A defence talk by ISRO Chairman S Somnath. He just goes over various aspects of space in relation to defence, particularly protection of space assets:
Re: Indian Space Program: News & Discussion
For a military person's perspective, a talk by Lt Gen Anil Bhat on defence and space in India:
Re: Indian Space Program: News & Discussion
India to launch ESA's Proba-3 spacecraft in December: Jitendra Singh
India will launch the European Space Agency's Proba-3 mission early next month from the spaceport at Sriharikota, Science and Technology Minister Jitendra Singh said here on Tuesday. Singh said the two satellites that are part of the Proba-3 mission to study the Sun were brought to Sriharikota on Tuesday morning for integration with ISRO's Polar Satellite Launch Vehicle (PSLV).
"Proba-3 mission of the European Space Agency will be launched by a PSLV rocket from Sriharikota in the first week of December," Singh said at the Indian Space Conclave organised by the Indian Space Association.
The mission is likely to be launched on December 4.
The two Proba-3 spacecraft will be launched together by the PSLV-XL launcher and placed in the highly elliptical orbit which will ascend to 60,000 km away from Earth before coming as low as just 600 km.
This high orbit is required because the pair of spacecraft will perform their active formation flying for a planned six hours at a time around their maximum altitude, where Earth's gravitational pull will be diminished, as will the amount of propellant needed to fine-tune their positions.
Proba-3's two satellites will enable sustained views of the Sun's faint surrounding atmosphere, or corona, that has previously only been visible for a few brief moments during solar eclipses viewed from the Earth.
To achieve this the shadow being cast between the spacecraft must remain in a precise position, which means they must fly autonomously in formation to an accuracy of a single millimetre - about the thickness of an average fingernail.
This is the first time that an ESA mission is being launched from India since the original Proba-1 Earth-observing mission in 2001.
Re: Indian Space Program: News & Discussion
How India Is Succeeding Where NASA Fails, and On a Tiny Budget
Re: Indian Space Program: News & Discussion
Deleted
Last edited by Suraj on 09 Nov 2024 23:35, edited 1 time in total.
Reason: Sports news in the space thread.
Reason: Sports news in the space thread.
Re: Indian Space Program: News & Discussion
With 7 more satellites, Isro plans to provide navigation signals to civilians' mobiles: INSPACe chairman - ToI
Isro is working to make India’s own regional navigation system (NaVIC) easily accessible to civilians soon, as the accurate positioning system was till now confined to strategic use, said Pawan Goenka, chairman of space regulator and promoter INSPACe. He also said that “by 2025, Isro will target to launch a dozen satellites every year, including six GSLV launches”, to fulfil the growing demand of the space sector.
“We are introducing seven navigation satellites with the new L1 band that will make NaVIC signals accessible in civilians’ mobile phones with a compatible chipset. Of the seven, one satellite has already been launched, six more will be launched. Navigation satellites launched earlier worked on different bands (L5 and S),” Goenka informed during a media roundtable.
He also said that NaVIC (Navigation With Indian Constellation) is more accurate than other navigation systems in the world and govt is working to widen its reach. NaVIC provides positioning accuracy of better than 10 metre throughout India and better than 20 metre for the area surrounding India by 1,500 km.
Announcements of creation of INSPACe, space policy and FDI policy have given a much-needed boost to the sector, the chairman said, adding, “our next objective is to bring in Space Law, which the country doesn’t have”. “We have prepared the first draft within dept. We will now send it for consultation and then it will go to the ministry for clearance before the cabinet approval. The entire process will be completed by either end of this year or by the first quarter of next year,” he said.
To grab a lion’s share of the $5.2 billion global small satellite market, Isro is planning to focus on small launchers and satellites, Goenka said. Isro’s mini-launcher SSLV has, therefore, been developed for this purpose and its technology will be transferred to the private sector in the next two years. Kulasekarapattinam spaceport in Tamil Nadu, which is being developed especially for small launches, will be ready in two years and will coincide with SSLV tech transfer to the private sector, he said.
The SSLV, together with small rockets of Indian startups AgniKul and Skyroot, will try to fulfil the growing demand for small satellites within and outside the country. Isro and the Indian startups will aim to launch around 25 satellites every year, he said.
With growing interest of youth in the space sector, INSPACe is also collaborating with universities to carve out full-year degree courses in space to meet the talent demand in the growing sector, Goenka said.
“In its promoter’s role , a Standing Committee for Inter-ministerial Coordination (SCMIC) of INSPACe meets every month to do authorisation and set targets. We are trying to set up a single-window system to fast-track clearances for applications of private companies. We have till now 566 applications from the private sector, including 67 for launchers and subsystems, 173 for satellites and 28 for ground segments,” Goenka said.
“We have currently planned to provide funding to eight startups of up to Rs 1 crore and also set up a tech centre for this purpose,” the INSPACe chairman said, adding that “we are also encouraging private companies to set up their own constellation of small satellites in space”.
With multi-front growth in the space sector, India's space economy is expected to touch $44 billion by 2033.
Re: Indian Space Program: News & Discussion
SpaceX is ISRO competition. India's share of the launch market is miniscule. Today SpaceX launches 87% of payload by weight worldwide. SpaceX is also the world foremost satellite manufacturer.
https://www.astralytical.com/insights/i ... g-catch-up
Cost per kg for SpaceX Falcon is 4 times cheaper than it's nearest competitor the CNSS CZ-2D or Russia.
https://www.astralytical.com/insights/i ... g-catch-up
Cost per kg for SpaceX Falcon is 4 times cheaper than it's nearest competitor the CNSS CZ-2D or Russia.
Re: Indian Space Program: News & Discussion
SpaceX launching 1st mission for Indian Space Research Organisation today - Space.com
SpaceX is set to launch its first-ever mission for the Indian Space Research Organisation (ISRO) today (Nov. 18).
A Falcon 9 rocket carrying ISRO's GSAT-N2 communications satellite is scheduled to lift off from Cape Canaveral Space Force Station today during a two-hour window that opens at 1:31 p.m. EST (1831 GMT). If it goes at the beginning of that window, it will be the third launch in 27 hours for Elon Musk's company.
SpaceX will livestream the action via its X account, beginning about 15 minutes before liftoff.
The Falcon 9's upper stage, meanwhile, will deploy the 10,360-pound (4,700 kilograms) GSAT-N2 in geosynchronous transfer orbit about 34 minutes after liftoff. The satellite — a project of New Space India Limited, ISRO's commercial arm — will then make its way to geostationary orbit, which lies 22,236 miles (35,786 kilometers) above our planet.
No Indian rocket can carry such a heavy payload to such a distant destination, according to India Today, so ISRO went with the Falcon 9. This marks a departure for the Indian space agency, which has generally gone with rockets operated by the European company Arianespace to loft its heaviest satellites.
Once GSAT-N2 is up and running, it "will provide vital services across the country, including internet connectivity for remote areas and in-flight internet services — an area that has recently seen regulatory changes allowing such connectivity in Indian airspace," India Today wrote.
Re: Indian Space Program: News & Discussion
SpaceX’s Falcon-9 places India’s Gsat-20 in orbit; satellite to boost communications infrastructure - ToI
SpaceX’s Falcon-9 rocket early Tuesday lifted off smoothly from Cape Canaveral Space Force Station in Florida, and placed India’s Gsat-20 or Gsat-N2, a high-throughput satellite that is designed to elevate communication infrastructure into a desired orbit.
The launch happened at 12.01 as planned, the satellite separated some 34 minutes thereafter, and was then placed in the orbit.
Weighing 4,700kg and engineered for a 14-year mission, the Gsat-20 represents a significant leap in satellite communication technology and as per Isro, the cutting-edge Ka-band high-throughput satellite is designed to transform broadband and in-flight connectivity across the region.
TOI had reported in the first week of Jan that India’s Space PSU NewSpace India Limited (NSIL) will launch Gsat-20 on Elon Musk’s SpaceX rocket later this year.
This is NSIL’s second demand-driven communications satellite and is primarily aimed at meeting India’s growing broadband connectivity needs.
NSIL will fully own, operate and fund the satellite, which can provide up to 48Gbps of capacity across 32 beams covering all of India including the Andaman, Nicobar, and Lakshadweep Islands.
NSIL CMD Radhakrishnan D had told TOI earlier: “SpaceX was selected against an RFP we had floated last year. There were other bidders too. This marks a new beginning as we launch on a US rocket from their soil. The present agreement is only for this launch and we will look at future requirements as and when we need.”
This is the first time that NSIL used a US launcher. The PSU has earlier made use of the services of France’s Arianespace. NSIL looks for services abroad when the weight of the satellite is higher than the capacity of Indian launch vehicles.
As part of the Indian govt’s space sector reforms announced in 2020, NSIL is mandated to build, launch, own and operate satellites that address service needs on demand.
In June 2022, NSIL successfully launched its first demand-driven satellite mission, GSAT-24 (now called GSAT-N1), which is fully leased by TataPlay. “While this is also a dedicated satellite, it is not meant for a single company. There are multiple players in the fray,” an official told TOI.
Re: Indian Space Program: News & Discussion
India's Chandrayaan-2 moon orbiter avoids collision with South Korea's Danuri spacecraft - Space.com
India's Chandrayaan-2 moon orbiter maneuvered in September to avoid a close approach with South Korea's Danuri spacecraft, according to a recent report from the Indian Space Research Organisation (ISRO).
The report said the Chandrayaan-2 orbiter raised its orbit on Sept. 19 to prevent a close approach to Danuri, which was expected to occur two weeks later if Chandrayaan-2's trajectory went unchanged. The report noted that a subsequent maneuver, which took place on Oct. 1, also helped Chandrayaan-2 avoid potential collisions with other orbiters around the moon, including NASA's Lunar Reconnaissance Orbiter (LRO).
Such collision-avoidance maneuvers are not uncommon around the moon. Chandrayaan-2, Danuri and LRO all share a nearly polar orbit, so the spacecraft come close to one another over the lunar poles, where the risk of collision is very high. In the last year and a half alone, the Korea Aerospace Research Institute (KARI), which operates Danuri, received 40 "red alarms" of potential collisions among LRO, Chandrayaan-2 and Danuri.
In 2021, Chandrayaan-2 shifted its orbit to avoid a predicted close approach to LRO over the moon's north pole. Without the maneuver, the two spacecraft would have crossed by one another at only 1.8 miles (3 kilometers) apart, ISRO said.
Re: Indian Space Program: News & Discussion
<poof>
Last edited by hnair on 30 Nov 2024 07:51, edited 1 time in total.
Reason: No posting of non-Indian programs. The place is international aerospace thread
Reason: No posting of non-Indian programs. The place is international aerospace thread